1. Field of the Invention
The present invention relates to an image reading device and an image reading method.
2. Description of the Related Art
There is a trend to promote computerization in recent years. This trend makes image processing apparatuses such as printers and facsimiles used to output computerized information and scanners used to computerize documents indispensable equipment. Such an image processing apparatus is typically configured as a multifunction peripheral having an image capturing function, an image forming function, a communication function, and the like and operable as a printer, a facsimile, a scanner, and a copier.
Among these image processing apparatuses, some type of scanners used to computerize documents is capable of reading two sides of a document simultaneously. Image data generated by a reading process is input to a circuit that performs various image processing on the image data. A frequency (hereinafter, “input frequency”) at which data can be input to this image processing circuit depends on performance of the image processing circuit.
Meanwhile, image data generated by the scanner as described above that performs two-sided reading is doubled in data amount. Accordingly, it is difficult to input the generated image data to the image processing circuit in real time due to the input frequency of the image processing circuit.
To solve such a problem, a method of providing a buffer upstream of the image processing circuit or a method of compressing image data generated by a reading process and inputting the compressed image data to the image processing circuit, which is disclosed in Japanese Patent Application Laid-open No. H9-130560 for example, is used.
However, the method of compressing image data disclosed in Japanese Patent Application Laid-open No. H9-130560 requires the image processing circuit, to which the compressed image is to be input, to decompress the compressed data before performing image processing. This leads to a problem such as an increase in circuit scale, and an increase in complexity of circuit logic which results in a decrease in processing efficiency and a decrease in input frequency incidental thereto.
When lossy compression is employed as a compression method, some data is lost, resulting in degradation in image quality. When lossless compression is employed, the image quality does not degrade but processing becomes complicated instead, causing the problems described above to arise.
Furthermore, there can be a case where an image processing circuit of a scanner performs pixel thinning to lower the resolution of read data to a resolution desired by a user. In this case, even when all read data is transferred using the compression or other method described above, pixel thinning is performed on the read data as specified by a user, making processing inefficient.
Therefore, there is a need for an image reading device and an image reading method to enhance efficiency in transfer of read-image data of a scanner capable of two-sided reading.